Olsztyn, on the Lyna River, is the capital of the Warmia-Masuria region of Poland. Olsztyn was a noted regional center of commerce on the road that once connected Warsaw with Königsberg (now Kaliningrad). The Medieval-era Old Town is a district which houses many examples of Brick Gothic architecture, and Olsztyn Cathedral has been called one of the most beautiful Gothic cathedrals in Poland. Another Gothic building, the Castle of the Warmian Bishops, dates from the 14th century and is now open to the public as a museum and a concert and cultural event venue. Olsztyn is also a popular jumping-off point for exploring the Masurian Lake District, where such lakes as Sniardwy, Poland`s largest lake, are located.